The present invention concerns a device for measuring wear in large roller bearings. Large roller bearings in the sense of the present invention are ball bearings, cylinder bearings, or combinations thereof that are hollow in that they are not provided with an essentially solid shaft. At least one ring is accordingly fastened to the main component by screws that parallel the bearing's axis of rotation.
The lives of all roller bearings, and accordingly of large roller bearings, are limited by the eventual destruction of their races or rollers. It is difficult to predict when this destruction will occur in that it depends to a large extent on the material, method of manufacture, and application. It usually begins with pitting, especially of the races, which are usually softer than the rollers. The pitting constantly worsens and leads to pea-sized or bean-sized fragmentation of the race. If the bearing continues in use, these fragments can in turn lead to larger-scale fractionation of the material that can suddenly freeze the bearing and lead to breakdown of the overall equipment, a shovel, crane, or bulldozer for instance.
Because of their size and the need to fit them to a particular piece of equipment, it often takes several months to individually manufacture large roller bearings for such applications. Since they are also often used far from where they are manufactured, it can also take several weeks to ship them. Downtimes of several months can accordingly be expected, and spare bearings must be kept on hand, an undesirable investment, especially if they are never needed because the originals turn out to last long enough.
German OS 2 418 056 discloses attaching a device to the bearing that indicates a prescribed displacement in one direction between the rings. There is, however, a drawback to this device in that it is mounted outside the bearing's accommodation and accordingly exposed to damage and destruction. It also depends on a probe with one end always resting against the relatively revolving ring, which can lead to wear over time and accordingly to misleading indications of a bearing problems that have not yet occurred.
U.S. Pat. No. 4,092,053 discloses inserting a probe through an opening in a bearing ring, whereby the end of the probe constantly slides over the relatively moving surface of the ring. The sliding motion, however, is not essential here because the probe is employed for determining weight and can regularly be replaced. Furthermore, weighing devices are easy to calibrate at any time. Still, this probe would be subject to the same drawbacks as the one disclosed in the aforesaid German OS 2 418 056 if it were employed for measuring wear.